The present invention refers to an apparatus for feeding bulk material, in particular to a rotary feeder of the type including a housing provided with a top inlet and a bottom outlet and accommodating a cellular rotor which includes a plurality of radial blades supported on a horizontal shaft and axially defined by respective lateral disks which are spaced from pertaining bearing covers by which the axial sides of the housing are closed, with a seal arrangement provided between each lateral disk and pertaining bearing cover of the housing.
A known seal arrangement for a rotary feeder of this type includes an elastic slide ring which extends between each lateral disk and pertaining bearing cover and is urged against the bearing-cover-facing side of the lateral disk. The use of such a slide ring is disadvantageous as it is subjected to unavoidable wear which is augmented with increasing contact pressure by which the slide ring is pressed against the end face of the lateral disk. The required contact pressure to act upon the slide becomes even greater with increasing pressure differential between the inlet port and the outlet port of the rotary feeder. A further drawback of such a slide ring resides in the difficulty to create a suitably long sealing gap in flow direction. The creation of a longer sealing gap is desired since the sealing action improves with longer and narrower sealing gap. However, a corresponding widening of the slide ring increases the danger of an uneven wear with increasing width of the slide ring.